For decades, our efforts to keep Earth’s excess carbon dioxide (CO2) out of circulation have focused on phasing out fossil fuels. But new, outside-the-box solutions are on the horizon – and, in some cases, locked under a kilometre of volcanic rock or even floating in vodka.
How did we get to this? Well, our best laid plans for cutting carbon emissions haven’t exactly panned out. The year 2025 was supposed to be when everything changed for the better.
Scientists said this would need to be the last year emissions peaked if we were to stand any chance of limiting the global temperature rise to 2ºC (35.6ºF), or ideally 1.5ºC (34.7ºC), by 2100.
But with 2024 emissions surpassing all records and average surface temperatures tipping over the 1.5ºC mark for the first time, it’s clear we’re off track. Way off track. Simply phasing out fossil fuels now isn’t going to be enough – we’ve left it too late.
“It would have been a good idea to have reduced demand for fossil fuels sharply 15 years ago, but we didn’t – and we’ve showed no signs of doing so,” says carbon capture and storage expert Prof Myles Allen from the University of Oxford. “So, I think we need to just get on with the alternative.”
The alternative being capturing greenhouse gases before they can do any more damage. That means hoovering up CO2 either directly from the air or from big emitters like power stations and locking it up so it can’t enter, or re-enter, the atmosphere.
For many scientists, carbon capture and storage is no longer a distraction from the real business of cutting carbon emissions. It’s critical to our route forward.
As Allen points out: “It’s an inescapable fact that we’re going to need to get rid of a lot of CO2 – in the order of a trillion tonnes – by 2100.”
The question is: how do we do it? Planting trees has always been the staple of carbon removal efforts. But natural ecosystems may not have the capacity we once thought and can’t quickly soak up the CO2 we’ve already unleashed.
A 2024 report by the University of Oxford’s research programme Oxford Net Zero contrasts ‘conventional’ CO2 removal methods with radical new approaches, like injecting CO2 into rocks.
While these novel methods currently account for less than 0.1 per cent of CO2 removal each year, they do include options that could lock away carbon on an effectively permanent basis – which trees can’t do. What’s more, there’s huge potential for expanding them.
Some of the alternatives, however, are whacky. We’ve rounded up the most promising – and weirdest – new solutions that could help us, before it’s too late.
1. Injecting volcanic rocks
Stationed on a lava plateau near an active volcano east of Reykjavík, in Iceland, the Orca plant is a mere dot on the landscape. But something epic is happening here.
Eight shipping container-sized boxes decorated with hundreds of large fans are sucking CO2 out of the cool, Icelandic air.
CO2 extracted from these collectors will be mixed with water, then injected 1km (0.6 miles) below the ground into volcanic rocks where it will, eventually, turn to stone.
Orca is the world’s first large-scale carbon capture and storage plant using direct air capture (DAC) technology.
Its owner, Climeworks, claims Orca and its larger sister plant, Mammoth – located nearby but not yet fully operational – could eventually remove 40,000 tonnes of CO2 from the air each year.
That said, recent reports suggest the company has not yet succeeded in offsetting its own emissions.
The shortfall seems to be related to the DAC part of the process, which is also pricey at $1,000 (approx. £738) per tonne of CO2. But with even bigger facilities set to dwarf the Iceland duo, costs could soon tumble.
In Texas, for example, Occidental Petroleum is building the mother of all carbon capture plants, designed to mop up half a million tonnes of CO2 a year – a quantity that could effectively “neutralise the climate impact of transport fuels in Europe,” Allen says.
And the turning CO2 to stone part? As mad as it sounds, it’s just a condensed version of a natural process called mineralisation.
Over centuries, basalt and other iron- and magnesium-rich rocks known as ‘mafic rocks’ – created when volcanic flows cool – soak up CO2, fixing it permanently in minerals through chemical reactions. Climeworks says its approach accelerates this process so that it takes just three years.
And while you might suppose volcanic rocks are rare, they actually make up most of the Earth’s 40km-thick crust.
Global storage capacity for CO2 in mafic (and ‘ultramafic’) rocks has been estimated at six quadrillion tonnes – the equivalent of that absorbed by 99 trillion tree saplings in 10 years’ growth.
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2. Abandoned salt mines
China’s Jiangsu province, north of Shanghai, is one of its wealthiest – and biggest emitters – thanks to thriving industries based on electronics, chemicals and cars. It is also, and has been since ancient times, a major salt producer.
Now, though, Chinese engineers propose to repurpose giant, hollowed-out caverns in its old salt mines to store some of the 800 million tonnes of CO2 Jiangsu pumps out each year.
The old Jintan salt mine in Jiangsu is the scene of 63 such caverns. Some of these have already been converted to store compressed air for a large renewable energy project where turbines are driven when air is released.
But the authors of a 2024 paper suggest other mines also meet the requirements for CO2 storage: large in size (over 200,000 cubic metres – which is about 53 million US gallons or 80 Olympic-sized swimming pools), with a capacity for deep burial (between 800–2,000m, or 2,600–6,500ft).
Unresolved issues include uncertainties about the pressure that CO2 should be stored at and how easily it can leak through salt.
Safety concerns are paramount; even though salt caverns have been used for decades to store natural gas and methane, they have not been without their hazards.
In 2001, an explosion at a salt cavern gas storage facility in Kansas, in the US, killed two people. Then, in 2020, a leak at a Mississippi cavern in the US vented 5,000 tonnes of methane – itself a potent greenhouse gas – into the atmosphere.
Still, the researchers behind the recent study estimate that if only a quarter of China’s abandoned salt caverns were used for CO2 storage, they could free up enough space for around 65 million tonnes – locking away the emissions of more than 15 million cars.
3. Whales, dead or alive
All living creatures store carbon in their bodies, but they’re not generally useful for locking it away long-term.
Most don’t live long enough and when they die they decompose, so the carbon they store goes back into the atmosphere too quickly to be helpful for combatting climate change. Whales, however, might be an exception.
“Just by virtue of being so big and long-lived, they can store a lot of carbon for a long time,” says marine biologist Prof Heidi Pearson from the University of Alaska Southeast, in the US. Pearson’s 2023 study focused on how restoring whale populations could boost CO2 storage.
With some species measuring over 30m (98ft) long and living for over 100 years, whales’ bodies can act as living, breathing carbon sinks.
Pearson’s work estimates that just eight of the 14 baleen species on the planet contain the equivalent of 7.3 million tonnes of CO2. That’s about the same as the emissions from burning nearly 17 million barrels of oil.
But that’s not all. Dead baleen whales dropping to the ocean floor (known rather poetically as ‘whale falls’) put away another 228,000 tonnes of carbon each year.
And while it’s not exactly clear how long it takes their carcasses to degrade, it’s thought that once they mix with deep-sea sediments, the carbon in them could stay submerged for millennia.
What’s more, nearer the surface, supersized whale poops act like fertiliser for microscopic marine organisms called phytoplankton.
“Like trees on land, the phytoplankton suck up CO2 from the air through photosynthesis,” Pearson says. And when they die, they too sink into the deep, taking their carbon stores with them.
Yet Pearson admits this won’t cut it alone. While restoring marine habitats is important, from a carbon perspective the “crisis moment” we’re now in demands a much larger suite of solutions.
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4. Vodka and tonic
Soft drinks producers are no strangers to carbonation. But the drinks industry is now starting to make mixers – and sterner stuff, including spirits – using CO2 sourced directly from power stations and other big emitters.
In the Nottinghamshire town of Worksop, UK, for example, staff at a new 10-megawatt plant supplying electricity to 10,000 homes capture CO2 in the plant’s exhaust gases and send it to the local pub.
The gas-fired plant traps CO2 in solvents as part of its standard operation, which is then cleaned and heated to release it from the solvent before eventually being compressed to form liquid CO2 for convenient storage.
The average gas-fired power station emits around 400,000 tonnes of CO2 each year, which sounds like a lot of bubbles. Though, as Allen notes, “You have to think carefully about the long-term fate of this carbon – if it goes in fizzy drinks, then it’s going back in the atmosphere.”
Meanwhile, in a New York City bar, you can down a cocktail containing vodka made from nothing but CO2 and water.
Brooklyn-based firm Air Company produces alcohol (as well as actual rocket fuels) by sourcing CO2 from a range of carbon emitters and combining it with hydrogen – extracted from water by electrolysis. The resulting drink doesn’t make for a cheap round, but it does come with a sense of moral superiority.
The idea of saving CO2 in drinks falls more under the category of carbon capture and ‘utilisation’ rather than storage.
But for those with big enough cellars – and wallets – building a vodka nest egg to bequeath to future generations could lead to a (very) niche storage solution.
5. In the walls
Concrete production emits so much CO2 that it’s hard to see how it could help us achieve net zero. Making cement, a key ingredient in concrete, puts around 1.5 billion tonnes of CO2 into the atmosphere each year, accounting for around 8 per cent of global carbon emissions.
But that’s exactly why scientists are so focused on it. Researchers and commercial companies are increasingly searching for ways to plough more CO2 back into concrete, curbing enough emissions to create materials they claim are carbon-negative overall.
Conventional concrete is made from cement and aggregates (traditionally sand and gravel). UK-based company Carbon8, however, makes its own aggregates from wastes like ash and then mineralises them in chemical reactions using CO2 collected from flue gases – a process akin to rock formation.
According to Carbon8, “If the reaction conditions are controlled, carbonation can be achieved in minutes instead of in the years taken for the natural reaction.”
The resulting carbon-enriched aggregates can be mixed with cement to produce concrete building blocks.
Captured CO2 can also be injected into concrete as it is starting to harden – during concrete ‘curing’ – an approach adopted by Canadian company CarbonCure.
US researchers calculated in 2021 that combining several different approaches for carbon capture in concrete could, in theory, result in the net removal of as much as 116kg of CO2 per tonne from the atmosphere, which is definitely better than the 131kg emitted per tonne in conventional production.
As with carbonated drinks and sustainable spirits, carbon-negative concrete blocks are considered carbon utilisation rather than storage. However, given buildings tend to last more than a lifetime, they could trap carbon for a century or longer.
6. Painting projects
In 2023, UK researchers announced they’d made ‘Green Living Paint’, a paint containing a microbe that soaks up CO2 from the atmosphere.
The paint was a mixture of clay, latex, water and a little-known, desert-dwelling bacterium called Chroococcidiopsis cubana. Like plants, and some ocean plankton, this bacterium uses CO2 as an input for photosynthesis to make its own food.
The paint has – so far – not made it to the market. Since then, however, another UK-based team has been lauded for its own living building paint.
The exact formulation is a closely guarded secret, but Cyanoskin’s distinctly organic-looking green coating is ‘algae-based’ and photosynthetic. It grows and thickens as it absorbs CO2 from the environment.
Cyanoskin was initially tested on buildings at Imperial College London and the team behind it claims that if all buildings globally were coated in the paint, CO2 emissions could be reduced by up to 18 per cent – wiping out all US emissions plus most of the EU’s as well.
But what if ‘algal green’ doesn’t complement your curtains? Well, you may be in luck: the company is planning to expand its colour range to other natural shades by incorporating different types of algae.
Meanwhile, in 2024, another carbon-capturing paint invented by NASA scientist Dr Tanya Rogers was crowdfunded to the tune of over $10,000 (approx. £7,380). It works a little differently, though.
Its absorbent properties come not from living organisms but from olivine – a greenish mineral often found in basalt, which takes CO2 from the air and turns it into carbonates. In short, it mineralises CO2 in a similar way to Iceland’s Orca plant.
Now sold by The People’s CO2 and suitable for everything from art projects and DIY to bridges and buildings, the company says the paint can “hold approx. half its weight” in CO2, taking two to three years to “fully saturate”.
Is painted furniture going to solve climate change? Probably not. But when it comes to creative carbon storage, we’re certainly not short of options.
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